Mounting filaments.



E. P. BEGKWITH.

MOUNTING PIEAMENTS.

APPLICATION FILED MAY 21, 1906,

IN/5555s; 4

Patented AM. '16, 1912;

Y shape, it is possible to secure ilhllTED dll l l fi llhaii lifih'l ELECTRIC COMPANY, A

EDWARD I. BECKW'ITH, OF SCHENECTADY, NE'W CORPORATION OF NEW YORK.

YlJR-K, ASSIGNOR T0 GENEEAL MOUNTING FIILAIJIENTS.

Application filed May :21, 1906.

To all whom it concern Be it known that I, EDWARD P. Bsonwrrn, a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in Mounting Filaments, of which the following is a specification.

This invention relates to lamps having filaments of non-ductile material, and to a process of mounting the filaments for use in a lamp.

It has been proposed to use tungsten, molybdenum and various other refractory metals as material for an incandescing conductor for incandescent lamps. The metals above enumerated. and others of a similar nature are usually obtainable in the form of powder and can be made into lamp filaments by first mixing with a small quantity of a suitable binder and then after shaping into filamentary form treating to remove. the binder and to sinter or agglomerate the residue into a coherent wire. i lthough this wire may be brittle and non-ductile and incapable of being readily bent or manipulated, it is serviceable as a light-giving source in an incandescent lamp. T he resist ance of a metal filament is such that when Specification of Letters Eatent.

used oncommercial voltages the filamentl must be of considerable length, and hence must be coiled up or arranged in some special manner to make it fit within lamp globes of ordinary style and size.

According to the present invention the metal or compound .of he metal is mixed or combined with a suitable binding material to make a. massor mixture which can be squirted or otherwise shaped intoa filament. The raw filament thus produced is then, strung on suitable sup-ports with proper allowance for subsequent contraction during treatment and is there subjected to whatever treatment is necessary to drive out the binding material, or otherwise render the filament refractory and suitable for use in the finished lamp.

The filament remains on the supporting though the final product is non-ductile and l coui not be bent or coiled to {he desired the desired loops 5, 6 and Patented Apr. lit, idliv.

Serial No. 317,923.

shape by when it is dition.

Although my process is applicable to a great variety of materials which are not ductile, I will describe the process as applied to one method of making tungsten filaments, and it will be understood that the novel features are equally applicable to other process-es of making tungsten filaments, or to processes of making filaments of other refractory materials.

Figure 1 is a perspective view of a supporting frame suitable for holding the lamp filament; Fig. 2 shows the raw and. unfinished filament in place on the frame; Fig. 3 shows the same frame and filament when finished and -mounted in the lamp bulb; and Fig. l shows a modified form of supporting frame.

To produce a tungsten filament I proceed by mixing tungsten and glucose to produce a plastic mass suitable for squirting through a die. To this mixture may be added one or more of the oxide of tungsten. As the mixture coines from the die the fila ment is sufficiently strong to support a considerable length of its own weight. While still soft it is hung in loops upon a frame of the general construction shown in Fl 1.. The supporting frame comprises a glass pedestal 1 carrying at its end a glass post 2 in the outer end of which nickel Wires 3 are seated. Another set of nickel arms project radially from the u per end of the bar 2 and serve as supports or the filament. These radial rods are grouped in pairs and each loop of the filament is supported on a pair of WilicS and is thereby protected-from sharp bends at the points of support. The filament takes the form of a plurality of 7 separated by the short horizontal stretches 8, 9 and 10- between hooks.

\Vhen the plastic, filaments are looped over the double hooks and allowed to hang around: the cylindrical glass rod, sufiicient slack is left. in the loops so that in case of a subsequent contraction of the filament it will not be ruptured. The loops are caught up and supported at the bottom by hooks turniug'inward and upward. in such amannew: that the loops may slip upward out of the hooks in case of: very great contraction.

in the raw or unfinished con The filament. may be fastened to the leads by a paste consisting of tungsten oxid and glucose. The frames may have three or four or even more loops according to the voltage of the lamp and the length of filament desired.

The next operation consists in drying the heretofore plastic filament to put it in condition for carbonization of the glucose.

This'step may be carried out by introducing the frame and filament in a resistance furnace and heating gradually to about 250 C. After a few minutes treatment the fila ment may be removed and placed in a sec- 13 0nd heater at a temperature of about 350 (3., to carbonize the glucose When this operation is complete the filament consists of a mixture of tungsten and carbon, and some oxid of tungsten'if the latter has been added to the original mixture. The frame and its filament may then be placed in a closed bulb and the air exhausted and a current passed through the filament to decompose the oxid and drive out some of the carbon in combination with the oxygen of the oxid, The remaining carbon may be removed by heating the filament in an oxidieing atmosphere to produce a film of oxid on the,filament and then heating to a highertenlperature in a reducing atmosphere to cause reduction of the oxid and combination of the oxygen with the carbon impurity of the filament.

The reactions and treatments above described produce a very marked contraction in the filament and take up the slack originally given to the loops, so that the finished 'fiiament assumes substantially the shape shown in Fig. 3. This figure shows the filament and its supporting frame mounted in a bulb 10 of ordinary construction and ready for use on commercial circuits. The filament though strong and well able to resist fracture from shocks due to transportationis nevertheless non-ductile and cannot be bent to any great extent without danger ofbreaking.

it should be noted that according to the process above described, the entire filament is made at the same time and consequently is of uniform composition throughout. In this respect it is much superior to the composite filaments which have heretofore been of the non-ductile material.

' I In the modification shown in Fig. 4 the "lamp stem 11 is provided with a bulb-like eniargement 12, in which are sealed the Head-wires 13 and the supporting metal made by cementing together short lengths incandescent lamps having ,filaments made from plastic material, which consists in suspending the filamcnt, while plastic, in loops on a supporting frame, treating said filament while on said frame to render the filament refractory and non-ductile, and then mounting said frame witlr-said filament incandescent lamps having filaments of complex configuration made from plastic material, which consists in so applying thefilamcnt while plastic to a sl.1p )orting frame as to give the filamentsubstantially the dcsircd configuration, treating said filament while on said frame to render it; non-ductile, and then mounting said frame with the filament thereon in the lamp bulb.

4. The process of manufacturing electric incandescent lamps having filaments made from plastic material composed of metal and a binder, which consists in suspending said filament, while plastic, on a supporting frame, treating said filament whileon said frame to remove the binder and to convert the filament into brittle metal, and then mounting said frame with the filament thereon in the lamp bulb.

5. A method of manufacturing electric incandescent lamps having filaments made from plastic material consisting in stretch-' ing the filaments while in a plastic condition on the support subsequently employed for supporting them in the lamps, in completing the manufacture of the filaments while on said supports, and in inscrtingthe supports with the finished filaments in the lamp bulbs. i

0. A.method of manufacturing electric incandescent lamps having filamentsmade from plastic material consisting .in squirt ing into the form of filaments plastic material consisting of powdered metal with a small quantitycnf a binding medium, in stretching the filaments while in a plastic condition on the support subsequently employed for supporting them in the lamps, in completing the manufacture of the filaments while on said supports, and in inserting the supports with the finished filaments in the lamp bulbs.

7. The method of manufacturing incandescent lamps having brittle filaments of.

metal which consists in supporting the filament while in an unfinished condition on a Support subsequently employed for supportmg it in a lamp and completing the manufacture of said filament while on said support.

8. The process which 'consists in moun ting'in lpoped form on its permanent supporting system a pliant filamentary body contaimng metal and binder and theretreating said body to remove the binderand to con- 10 vert the body into a brittle metal filament.

' In witness whereof, I have hereunto set my hand this 19th day of May, 1906.

EDl/VARD P. BECKW ITH.

Witnesses:

BENJAMIN B. HULL, HELEN Onronn. 

